Chemical feeder



April 20, v1954 w ),iHU/GHES CHEMICAL FEEDER Filed Jan. 6, 1949 2 Sheets-Sheet l April 2o, 1954 w. J. HUGHES 2,675,758

CHEMICAL FEEDER y Filed Jan. 6, 1949 2 SheebS-Sheei'I 2 j vxmimw Patented Apr. Z0, 1954 CHEDIICAL FEEDER Walter J. Hughes, Chicago, Ill., assigner to Infilco Incorporated, Chicago, Ill., a corporation of Delaware Application January 6, 1949, Serial No. 69,500

12 claims. 1

This invention relates to improvements in chemical feeders of the diaphragm type in which the displacement of the feeder is proportional toy the stroke, and more particularly relates to a. new and improved diaphragm pump adapted to accurately meter small quantities of chemical solutions.

The principal object of my invention is to provide a novel and simplified form of diaphragm pump controlled by a constant speeed motor and so constructed and arranged as to effect a uniform flow of chemicals at various desired rates, with a high degree of accuracy.

Another object of my invention is to provide a diaphgarm pump operated by uid under pressure equally distributed over one face of the diaphragm so as to effect instantaneous operation of the diaphragm and so constructed and arranged as to produce a dwell between the strokes f the diaphragm, to effect a positive valve action upon each stroke of the diaphragm.

A more specific object of my invention is to provide a diaphragm pump in which the pressure strokes of the diaphragm are effected by the uniform application of fluid under pressure such as air, over one face of the diaphragm, to attain free and positive pressure stroke action of the diaphragm, and in which the diaphragm may be returned on its suction strokes by its own resiliency or by means of a spring, upon the release of pressure therefrom.

Another object of my invention is to provide a diaphragm pump having a novel form and arrangement of self cleaning check valves, so constructed as to attain positive opening and closing of the valves with a minimum obstruction to the flow of fluid through the valve ports, so as to attain free passage of fluid through the valve ports.

A further object of my invention is to provide a new and improved form of diaphragm pump wherein the valve ports, valves, pump chamber and diaphragm are so constructed and arranged as to provide a self-air-eliminating and selfpriming pump against a. substantial suction lift, as well as against a substantial discharge head.

Still another object of my invention is to provide a novel form of fluid pressure operated diaphragm pump utilizing a exible diaphragm preformed in the shape it will assume at the ends of its suction strokes and uniformly conforming to the wall of the pump chamber at the ends of its pressure strokes, with a minimum amount of stretching, so as to secure uniform engagement of the diaphragm against the entire wall surface of the pump chamber, and to assure complete evacuation of duid therefrom.

A still further object of my invention is to provide a consta-nt flow diaphragm pump which may be accurately regulated to attain variousy desired flows of liquid, and to provide a simple means for setting the rates of delivery thereof.

A further object of my invention is to provide a novel form of diaphragm pump in which the discharge of liquid may be quickly and easily regulated by varying the length of the strokes of the diaphragm.

Still another object of my invention is to provide a new and improved chemical feeder, including two pumps in a single casing operated from a single source of power and having independently controllable displacements, to dispense two different liquids.

These and other objects of my invention will appear from time to time as the following specication proceeds and with reference to the' accompanying drawings wherein: 1

Figure 1 is a plan view of a chemical feeder constructed in accordance with my invention with part of the top cover removed and certain parts of the feeder casing shown in horizontal section;

Figure 2 is a longitudinal sectional view of a control valve for the chemical feeder, taken sub.- stantially along line 2-2 of Figure 1;

Figure 3 is an enlarged detail plan view of a rotatable valve disk used in the valve shown in Figure 2;

Figure 4 is a sectional view taken substantially along line I-c of Figure 3;

Figure 5 is a vertical sectional View of one of the pumps shown in Figure 1, and taken substantially along line -5-5 of Figure 1; and

Figure 6 is a vertical sectional view illustrating a modiiied form of pump constructed in accordance with my invention.

In the embodiment of my invention illustrated in Figure 1 of the drawings, two pumps I9 are shown as mounted on the outside of a casing I l and extending thereinto. Each of saidV pumps may be of a similar construction so one only need herein be shown and described in detail. The casing l I is provided with a removable cover I2 and has a motor l5 suitably mounted on its bottom. Said motor may be an electric motor of a constant speed type7 and is connected to rotatably drive a pump control valve i6, mounted on the bottom of the casing Il, at one side of said motor. Said pump control valve i 6 is herein shown as being of a rotary type and serves to release from the pumps IQ, through a ntting 2t connected with a head 2l of said valve, and communicating with a passageway 22 leading therethrough to a rotatable valve disk 21, seated against the inside face of said head. Said valve disk may be made from steel or brass or from one of the well known forms of anti-friction ma-A terials, one suitable material being that known to the trade as Graphitan The valve disk 21 is rotatably driven from the motor I5 through a reducer 23, which may be of any well known type, so is not herein shown or described in detail. Said reducer is connected with the valve shaft 2s through a coupling 25. Said shaft 24 is journaled in a casing 26 for the valve and has a drive member 28 secured thereto. A sleeve 29 is mounted on and driven by said drive member and extends therefrom toward the head 2|. The valve disk 21 is slidably mounted within said sleeve and has outwardly projecting pins 3|, slidably engaging diametrically opposed slots in said sleeve. Said valve disk 21 is slidably engaged with the inner surface of the head 2l by a compression spring 30, seated in the member 28 at one of its ends and in the inner side of the valve disk 21 at its opposite end. The inner surface of the head ZI is accurately machined and ground to form a fluid tight seat for said valve, and said valve disk 21 is held against said seat by said spring at all times, soas to maintain a tight joint therebetween.

The valve disk 21, as herein shown, has a diametrically extending passageway 33 formed in its face, which slidably engages the seat formed by the inside of the head 2i Said passageway is closed by said seat and may be enlarged laterally at its opposite ends to give the required time for the pressure strokes` of the pump. The inlet passagewayV 22 leading through the head 2 I, registers with the, center of the passageway 31%, so as to supply iluid thereto at all times. The pressure passageway 33 registers adjacent its ends with a pressure passageway 32 in the head 2i, twice during each revolution of the'valve disk 21. Said pressure passageway 32 extends through the head2 I Afrom the inner to the outer side thereof and is suitably connected to the pressure line I1, to alternately admit iiuid under pressure to and release iluid from the two pumps I8, to operate said pumps. The valve disk 21 is also provided with two exhaust passageways formedby diametrically opposed notches 35 extending therethrough. The exhaust passageways S'a'serve to relieve pressure from the pressure passageway 3.2 and the pumps Iitwice during each revolution of said valve disk. Fluid released from the exhaust passageways 35 passes to the inside of the sleeve 29 and out through the slots formed Vin said sleeve, and througha relief opening 36, provided inthe valve casing 26.

- It should here be understood that the passageway -33 need not be diametrical and that its arrangement may be varied with respect to the discharge passageways 35, to change the timing diaphragm lil on its suction strokes.

of the pumps, and that the elongated ends of said passageway may also be lengthened or shortened, to vary the time pressure is applied to operate the pumps I0, and to provide a dwell at the ends of the pressure and suction strokes of said pumps to insure instantaneous and positive opening and closing of the pump valves and an accurate displacement of the pump, as will hereinafter more clearly appear as this specification proceeds.

Each pump le, as shown in Figure 5, includes a body or block 39 having a diaphragm 40 extending across its inner end, and clamped thereto by means of a head M. Said head 4I is engaged with said diaphragm and may be secured to said body, as by machine screws 42. Said head QI is herein shown as being flanged as indicated by reference character 43, and the anged portion thereof is adapted to abut the outside of and be suitably secured to anouter wall of the casing I i, to support the body of said pump on the outsideof said casing. The pressure and discharge ends of the pumps Il) are thus readily accessible, to facilitate the connection to and disconnection of chemical lines (not shown) to and from said pumps.

The body 39 of the pump I is provided with a pumping chamber 44 formed therein, in alignment lwith a recessed portion of the head QI, forming a pressure chamber 45, separated from the chamber All by the diaphragm 40. The pumping chamber 4d is herein shown as being of a concave substantially hat-shaped formation, with a relatively deep Acentral depression and a slightly inclined annular brim.

The diaphragm 40 may be made of any well known elastic material, resistant to the chemicals to be fed, one form of material satisfactory for use in such pumps being neoprene. Said diaphragin may be preformed, as by molding, into the shape it will assume at the end of its suction stroke, so the yieldability of. said diaphragm will urge it to move in the direction of its suction strokes, and to completely iill the pumping chamber d at the end of each pressure stroke. Said diaphragm, as herein shown, may have a flat brim Ywhich is clamped between the block 39 and head 4I, and may have an annular inclined portion within said brim. Said inclined portion may extend at an opposite angle to the angle of the brim of the chamber 44, when said dia-f phragm is at the end of its suction stroke, to normally urge said diaphragm into the retracted position shown in Figure 5. Said diaphragm also has a central dome-shaped portion conforming to the central depression of the pumping chamber de and completely lling said depression at the end of eachpressure stroke of the pump. The thickness of said annular inclined portion of said diaphragm increases slightly toward said dome-shaped central portion, to avoid the tendency of said diaphragm to bulge when pumping against a negative head, and to insure a uniform pumping action of said diaphragm under various pressure conditions. Y

A machine screw 41 isvembedded in the enlarged-central portion of the diaphragm 40 and extends within a spring chamber A9 formed in the head di. A rod or spacer V50 is herein shown as being threaded on said machine screw and as extending .withinv said spring chamber.. vA compression spring 5I is provided to move the Said spring is relatively light, and since the resiliency of said diaphragm 4G will urge. it in the direction of its suction strokes, the Spring could be dispensed with when pumping 4under low heads. Said spring encircles the rod 50 and abuts the inner end of the spring chamber 49 at one of its ends. The opposite end of said spring abuts a disk or washer 53, secured to said rod 5!! by a machine screw 5d, threaded in said spacer. Fluid under pressure is admitted to the recessed portion i5 of the head di., to actuate the diaphragm it on its pressure strokes, through a pressure passageway 55 extending through said head and connected with the pressure line i9. Substantial clearance is provided between the diaphragm it and the walls of the pressure chamber or recessed portion t5 of the head di, when the diaphragm is at the ends of its suction strokes, to permit fluid under pressure to be uniformly distributed over one face of said diaphragm and instantaneously move it into uniform; engagement with the wall of Jthe chamber lili, so as to uniformly nil and completely evacuate said chamber at the ends of the pressure strokes of the pump.

Chemical solution is admitted to the pump chamber through an intake fitting 5l'. Said f1tting has an enlarged annular inner end portion which abuts a valve guide 59 at its inner end. Said valve guide 59 is mounted in a shouldered end t@ or the valve body 39. The iitting 5l and valve guide EQ are secured to the valve body 3S by means of an internally threaded coupling Si, having engagement with an outer shouldered portion of said iitting. The passageway through the tting 5l opens at its inner end into a valve chamber B2 formed by the enlarged inner end of said iitting. The inner end of the passageway through said fitting d? serves as a valve port and is formed into an annular valve seat t3 spaced inwardly from the wall of the valve chamber 653. The annular seating surface of said valve seat 3 is of a convex formation and is adapted to be engaged by the outer edge of an inlet valve member S4, interposed between the valve guide 5e and seat t3. Said inlet valve member iid may be made from a pliable material, such as neoprene, and is herein shown as being of a concave or umbrella-shaped formation, with a relatively thick inner portion tapering toward its periphery, so as to have a rigid interior and a pliable periph.- ery. Pressure on said inlet valve member Ed, during the pressure strokes of the diaphragm lt-i, will therefore rmly engage the outer pliable concave portion of said inlet valve member de with the convex surface of the seat t3, with a uniform sliding or wiping action. Said inlet valve meniber will thus wipe all foreign matter from the seat t3 upon closing, and the greater the pressure on said valve member from the chamber dit, the greater will be the seal between said valve member and seat. Said inlet valve member @d has a stem t5 extending in a direction away from its concave portion, and slidably guided in the valve guide 59. The valve guide 59 is apertured as indicated by reference character 65, to allow for the free passage of liquid therethrough. An inist passage 59 leads from the valve guide 5s to the pumping chamber id through the flat annular portion thereof, and extends to the concave portion of said pumping chamber.

A discharge passageway it leads from the ccncave portion of the pumping chamber it and connects the delivery side of said pumping chamber with a valve chamber 'i l formed on the opposite end of the valve block 3S from the fitting 5?. An annular valve seat 73, having a convex seating surface like the valve seat 63 is formed at the 6. outer end of said passageway 10. Said valve seat is adapted to be engaged by an outlet check valve member 14, which is of an umbrella-shaped formation, formed like the inlet valve member E4 and slidably guided in a valve guide 15, spaced outwardly from said valve seat. The valve guide 15 is held in position in the valve block by means of a fitting 'i6 abutting the outer face of said guide, and a coupling 'il threaded in an end of said block and engaging said fitting. Said outlet valve member 'it is thus engaged with the valve seat 73 with a sliding or wiping action by the suction created in the chamber 4, upon the suction strokes of the pump and forms a selfcleaning positively acting check valve.

It may be seen from the foregoing that the check valves just described are of a light pliable construction so as to instantaneously open and close with a minimum amount of pressure and suction, upon the suction and pressure strokes of the pump, to permit the free flow of liquid into and from the pump, and that the valve it is so constructed as to provide a positive dwell at the ends of the suction and pressure strokes of the pump, to cause said check valves to instantaneously and positively act to open or close the desired port. Also, said check valves, being of a pliable construction, become more firmly seated the greater the suction or pressure exerted thereon, and when the pump is in the position shown in Figure 5 close their respective passageways when the pump is not in operation. rlhis avoids siphcning through the pump and avoids the trapping of air therein, and also assures the retention of liquid in the pump chamber, brought therein upon the suction strokes of the pump by the action of the spring 4i. The pump l@ will thus be self -priming and will immediately start pumping upon operation of the diaphragm d.

A means is provided to accurately control the rate of discharge of the pump, 'which is herein shown as being a square threaded screw '59, movable to form an adjustable stop for the diaphragm iid, and to vary the lengths of the suction strokes thereof. Said screw is herein shown as being threaded within an internally threaded spacer 8G, secured to the outer end of the head l i Said screw is also feathered on a shaft di, journaled in a capl 83, secured to said spacer and abutting the outer end thereof. A disk 84 is secured to the outer end of said shaft, to rotatably move said shaft and move the screw 'le with respect to the disk t3. Said disk as shown in Figure 1, may extend through a slot @5 formed in the cover l2, and may be calibrated along its outer periphery with respect to an indexing mark on said cover, to designate the desired now of solution through the pump. The displacement of the pump may therefore be accurately adjusted from the outside of the casing at will. The pitch of the threads of the screw i9 may be such that one revolution of said disk 84 may move said screw from an extreme inward position, where there will be no now of liquid through the pump, to the extreme outward position shown in Figure 5, where there will be a maximum flow of liquid through the pump.

In operation, the motor l5 is started to operate the feeder. This will rotatably drive the valve disk 21 and admit fluid under pressure to each pump through the passageways 35, 32 and the pipes il and l 9. Twice during each revolution of said valve disk 2T, fluid under pressure in the pressure chamber 45 will act on the diaphragm di! throughout its eective area, to instantaneously move said diaphragm on its pressure strokes. Upon each pressure stroke of the pump, pressure in the chamber 44 and passageways t?! and 'it will close the inlet check valve 54 and open the discharge check valve 14, to permit the passage of liquid therethrough and through the tting 76, for use. The exhaust passageway 35 formed in the valve disk 21 will also register with the passageway 32 twice during each revolution of said valve disk 2l. This will relieve pressure from the chamber i5 and permit the spring 5I to move said diaphragm it on its suction strokes. During the suction strokes of said diaphragm, suction in the pumping chamber 44 will open the check valve &3 and will close the check valve 14.

In the modified form of my invention shown in Figure 6, the pump is somewhat similar to that shown in Figure 2 except that a second diaphragm 8l, of a larger effective area than the diaphragm 4G, is provided. This form of my invention requires less pressure to operate the pump than is required to operate the pump shown in Figure 5 and is particularly adapted for use where it is necessary to lift against greater heads than could be eiciently handled by the pump shown in Figure 5. The pump shown in Figure 6 is of the same general construction as that shown in Figure 5, so a description of the parts described before need not be repeated, and the same part numbers have been applied to similar parts in each of said figures. In Figure 6, the pump is shown as having a fianged head 88, which clamps the diaphragm 4&3 to the valve block 3S. A spacing member t9 is secured to said diaphragm by means of the machine screw lil. Said spacing member has a flanged outer end and is encircled by a spring 9%, seated within a recessed portion of the head 33 at one of its ends, and abutting the flanged portion of said spacing member at its opposite end, and -urges the diaphragm 40 in a direction away from the chamber d4, to effect the suction strokes thereof, upon the release of pressure from the diaphragm 87. A hollow anged member' 93 is shown as being secured to the outer side of the head 8B as by machine screws 94. While the flanged member 93 and head S8 are herein shown as being separate parts, it should be understood that they may as well be integrally formed. The hollow inside portions of said flanged member and head form a chamber open to the atmosphere, within which the spacing member 5 moves. The outer end of said chamber is closed by the diaphragm Si extending thereacross. Said diaphragm 8'! may be made from any resilient or pliable material, and is preformed into the shape it will assume at the ends of its suction strokes. Said diaphragm 87 is clamped into engagement with the anged portion of said flanged member by means of a cap 95, secured to said hanged member 93 bymachine screws i. Said cap has a central recessed portion S6 forming a pressure chamber, the outer wall of which is spaced from the diaphragm, when said diaphragm is in a retracted position, to provide clearance and permit fluid under pressure to uniformly engage said diaphragm throughout its entire area at the beginning of the pressure strokes of the pump. A diaphragm plate |00 serves to clamp said diaphragm to the anged portion of the spacing member 39, to cause said diaphragm to positively move said spacing member and the diaphragm Gli on its pressure strokes, upon the application of pressure to the diaphragm 87 in the chamber Q5. Said diaphragm plate ill is held in engagement with said diaphragm 81 by a machine screw IUI, threaded in the outerl end of the spacing member 89. A pressure passageway IUS enters the chamber 96, to supply pressure to said diaphragm and positively move said diaphragm 40 on its pressure strokes, against the spring Sil. The suction strokes of said diaphragm 40 are effected by means of the spring upon the release of pressure from the chamber 96, through the pressure passageway 103. A threaded stop |05 is adapted to engage the retaining plate lll, to adjustably limit the suction strokes of said diaphragm 46. Said stop is threaded within the cap and is feathered on a shaft I, journaled in an end closure member |07 for the cap 95. Said shaft and stop may be operated by a control disk like the disk 84 (not shown).

It may now be seen that a novel form of chemical pump of a simpliiied and improved construction has been provided, to accurately feed small quantities of chemical solution proportional to the stroke of the pump, which includes a preformed diaphragm, formed so as to be urged in the direction of its suction strokes by its own resiliency and to ycompletely ll the pumping chamber with a minimum amount of stretching upon its pressure strokes, so as to positively evacuate all of the liquid from said pumping chamber at the end of each pressure stroke.

It may further be seen that said diaphragm is actuated on its pressure strokes by the uniform application of uid under pressure thereto throughout its entire area, and may be returned on its suction strokes by its own resiliency or may be returned by means of a spring when pumping against a substantial head, and that the valve controlling the admission and release of fluid under pressure to and from said diaphragm is so arranged as to provide a dwell at the end of each pressure and suction stroke, so as to secure an instantaneous and more positive action of the pump valves than formerly and thus to increase the accuracy of the pump.

It may also be seen that the inlet and outlet valves of the pump are of a simplied form of yieldable check valve, so arranged as to permit the free flow of liquid therethrough, and to positively engage their respective seats with a uniform wiping action, so as to keep the valve seats clean by the wiping action of the valve and to assure that there will be no leakage of liquid thereby, when in closed positions.

It may still further be seen that this arrangement of valves and diaphragm assures the utmost accuracy in pumping the desired quantities of solutions and avoids siphoning when the pump is not in operation, and also assures that the pump be self-priming and self-air-elminating.

While I have herein shown and described several forms in which my invention may be embodied, it should be understood that I do not wish to be construed as limiting myself to the forms shown, except as expressly limited in the appended claims.

I lclaim:

1. In a chemical feeder, a casing having a concave inner wall forming a pumping chamber, a head for said casing having a recessed portion in alignment with said chamber, an elastic diaphragm extending across said casing and clamped in position by said head, said diaphragm being preformed in the shape it will normally assume at the ends of its suction strokes and to unin formly conform to the contour of said chamber without substantial stretching at thefends of its pressurestrokes, to completely evacuate liquid therefrom, a valved liquid inlet to and a valved liquid outlet from said pumping chamber, a spring seated in said head and operatively connected with said diaphragm, to move said diaphragm on its suction strokes, an inlet into said recessed portion of said head, means including a motor driven valve for alternately admitting duid under pressure to and releasing pressure from said inlet, to move said diaphragm on its pressure strokes, and to permit said spring to move said diaphragm on its suction strokes, clearance being provided between said recessed portion of said head and said diaphragm when said diaphragm is at the extreme ends of its suction strokes, to permit pressure to be uniformly distributed over the face of said diaphragm opposite from said chamber at the beginning of its pressure strokes.

2. In a chemical feeder, a casing having a ccncave inner wall forming a pumping chamber, a head for said casing having a recessed portion in alignment with said pumping chamber, an elastic diaphragm extending across said chamber and clamped in position by said head, said diaphragm being preformed in the shape it will normally assume at the ends of its suction strokes and being arranged to conform to the contour of said chamber at the ends of its pressure strokes with out substantial stretching, to completely evacuate liquid therefrom, a valved liquid inlet to said pumping chamber, a valved liquid outlet therefrom, a spring operatively connected with said diaphragm to move said diaphragm on its suction strokes, a fluid pressure inlet into said recessed portion of said head, means for alternately connecting said fiuid pressure inlet to a source of fluid under pressure and to atmosphere, said means including a motor driven valve connected to said inlet, the inner wall of said recessed portion of said head being spaced from said diaphragm to provide clearance between said diaphragm and said inner Wall at the ends of its suction strokes to uniformly distribute pressure over the face of said diaphragm opposite from said pumping chamber at the beginning of its pressure strokes, and a stop adjustable to vary the length of the strokes of said diaphragm and the displacement of said pump.

3. In a chemical feeder, a casing having a concave inner wall forming a pumping chamber, a head for said casing, an elastic diaphragm extending across said casing and pumping chamber and clamped in position therein by said head, said diaphragm being preformed into the shape it will normally assume at the end of each suction stroke and to uniformly conform to the contour of said inner wall at the end of each pressure stroke without substantial stretching, a spring operatively connected with said diaphragm to move said diaphragm on its suction strokes, valve means adapted to admit iiuid under pressure to the side of said diaphragm opposite from said pumping chamber to move said diaphragm on its pressure strokes, a screw threaded within said head and adapted to form a stop for said diaphragm on its suction strokes and to determine the length of the strokes of said diaphragm and the displacement of said pump, a manually operable control disk for rotating said screw, the pitch of said screw being such that one complete revolution of said disk will adjust the strokes of said diaphragm from a no-pumping condition to a maximum pumping condition.

4. In a chemical pump, a casing having a chamber formed therein, a flexible diaphragm dvid 10 ing said chamber into a pumping chamber ori one of its sides and a pressure chamber on its opposite side, a fluid pressure inlet to said pressure chamber, a spring connected with said diaphragm to move said diaphragm on its suction strokes, said pumping chamber being of a substantially hat-shaped form with a relatively deep concave central depression and an annular flatly inclined brim leading from the edge thereof, said diaphragm being preformed in the shape it will normally assume when completely retracted Yat the ends of its suction strokes and having a central convex projecting portion conforming to the form of said concave central depression of said pumping chamber and adapted to completely` fill said central depression at the end of each pressure stroke of the pump, and said diaphragm having an annular flatly inclined portion extending outwardly from said central convex portion at the same angle to the horizontal as said annular brim of said pumping chamber, but extending in an opposite direction to the horizontal when said diaphragm is in a retracted position so as to urge said diaphragm in the direction of its suction strokes by its own resiliency, clearance being provided between said diaphragm and the Walls of said pressure chamber to uniformly distribute pressure over the entire face of said diaphragm adjacent said pressure chamber at the beginning of its pressure strokes.

5. In a chemical pump, a chamber having a concave inner wall, a reciprocable flexible diaphragm extending across said chamber and formed to conform to the shape of said concave wall when in an extended position, and dividing said chamber into a pressure chamber on the side of said diaphragm opposite said concave wall and a pumping chamber on the side of Fsaid diaphragm adjacent said concave wall, a

liquid inlet to said pumping chamber, a liquid outlet therefrom, valve means in said inlet and said outlet, a spring operatively connected with said diaphragm to move said diaphragm on its Vsuction strokes, a fluid inlet to said pressure chamber, means for alternately supplying iuid under pressure to and releasing fluid from said pressure chamber including a motor driven valve, a stop screw adapted to determine the length of the strokes of said diaphragm and the displacement of said pump, and a control wheel operatively connected to rotate said screw, the pitch of said screw being such that one revolution of said control wheel will vary the length of the strokes of said diaphragm from a no-pumping condition to a maximum pumping condition.

6. In a chemical pump, a pumping chamber, a reciprocable diaphragm extending across said chamber and preformed into the shape it will assume at the ends of its suction strokes and to completely fill said chamber at the ends of its pressure strokes Without substantial stretching, spring means for operating said diaphragm on its suction strokes, an inlet to and an outlet from said pumping chamber, check valves in said inlet and said outlet, each of said check valves including a check valve member and an annular valve seat, means to assure complete and instantaneous opening and closing of said check valves and an accurate displacement of said pump including a motor driven valve connected to admit fluid to operate said diaphragm on its pressure strokes and to release uid therefrom at the beginning of its suction strokes, said motor driven valve being so constructed and arranged as to provide predetermined dwells at the endsY of the strokes of said diaphragm to assure positive and instantaneous opening and closing of said valves, said check valve members being of a pliable umbrella-shaped formation adapted to engage their respective valve seats with a uniform wiping action.

7. In a chemical pump, a pumping chamber, a reciprocable diaphragm extending across said chamber and preformed into the shape it will assume at the ends of its suction strokes and to completely ll said chamber at the ends of its pressure strokes Without substantial stretching, spring means for operating said diaphragm on its suction strokes, an inlet to and an outlet from said pumping chamber, check valves in said inlet and said outlet including an annular valve seat therein having a convex seating surface and a pliable check valve member engageable with said seating surface, said check valve members being of an umbrella-shaped formation and having guide stems extending therefrom in directions away from their seats, and means to assure complete and instantaneous opening and closing of said check valves in the desired sequence and an accurate displacement of said pump including a motor driven valve connected to admit fluid under pressure to operate said diaphragm on its pressure strokes and to release fluid therefrom at the beginning of its suction strokes, said motor driven valve being so constructed and arranged as to provide predetermined dwells at the ends of the strokes of said diaphragm to assure positive and instantaneous opening and closing of said check valves upon reversal of the strokes of said diaphragm.

8. In a chemical pump, a pumping chamber having a concave inner wall, a reciprocable diaphragm extending across said chamber and preformed into the shape it will assume at the ends of its suction strokes and to completely fill said chamber when in an extended position Without substantial stretching, spring means for operating said diaphragm on its suction strokes, an inlet to and an outlet from said pumping chamber, check valves in said inlet and said outlet, each of said check valves including an annular valve seat with an annular convex seating sur.. face, a valve guide spaced from said seat, a pliable check valve member of an umbrella-shaped formation interposed between said guide and said seat, said check valve member having a stem extending from one of its sides and guided in said valve guide, and having an opposite concave side slidably engageable with said convex seating surface of said valve seat with a uniform wiping action, and means assuring positive and instantaneous opening and closing of said check valves in the desired sequence and an accurate displacement of said pump including motor driven valve means connected to admit fluid under pressure to operate said diaphragm on its pressure strokes and to release pressure therefrom at the beginning of its suction strokes, and being so constructed and arranged as to provide predetermined dwells at the ends of the strokes of said diaphragm to assure positive and complete opening and closing of said check valves upon the reversal of the strokes of said diaphragm.

9. In a chemical pump, a casing, two spaced diaphragms in said casing connected to move in unison and separating said casing into a pumping chamber on one side of one diaphragm, a

pressure chamber on the opposite side of the .other diaphragm, and a spring chamber between said diaphragms and connected to atmosphere, a spring in said spring chamber connected to move said diaphragme in one direction, said diaphragms being preformed into the shapes they will normally assume at the ends of their suction strokes, said one diaphragm being so shaped as to completely ll said pumping chamber at the end of its pressure strokes without substantial stretching, and said other diaphragm having a larger eiiective area than said o-ne diaphragm, valved inlets and outlets to and from said pumping chamber, a pressure inlet to said pressure chamber, means for alternately connecting said inlet to a source of fluid under pressure and to atmosphere, and clearance being provided between the walls of said pressure chamber and the adjacent face of said other diaphragm, whereby pressure may be uniformly applied to the entire area of said other diaphragm at the beginning of the pressure strokes of the pump.

1G. In a chemical pump, a casing, two spaced diaphragms in said casing connected to move in unison and separating said casing into a pumping chamber on one side of one diaphragm, a pressure chamber on the opposite side of the other diaphragm, and a spring chamber between said diaphragms and connected to atmosphere, a spring in said spring chamber connected to move said diaphragms in one direction, said diaphragms being preformed into the shapes they will normally assume at the ends of their suction strokes and being urged in the direction of their suction strokes by their own resiliency, and said diaphragm separating a part of said casing into a pressure chamber having a larger effective area than said diaphragm separating a part of said casing into a pumping chamber, and said diaphragm separating a part of said casing into a pumping chamber being so shaped as to completely nll said pumping chamber at the ends of its pressure strokes without substantial stretching, valved inlets and outlets to and from said pumping chamber, a pressure inlet to said pressure chamber, means for alternately connecting said inlet to a Source of uid under pressure and to atmosphere, clearance being provided between the walls of said pressure chamber and the adjacent face of its associated diaphragm, whereby pressure may be applied to the entire area of said associated diaphragm at the beginning of the pressure strokes of the pump, and an adjustment screw forming a stop to vary the length of the strokes of said diaphragms and the displacement of said pump.

l1. In a chemical pump including a pumping chamber, a reciprocable pumping member, means for reciprocating said pumping member into and out of said pumping chamber, an inlet to said pumping chamber and an outlet from said pumping chamber, self-cleaning check valves in said inlet and said outlet, each of said check valves comprising an annular valve seat having a convex seating surface, an umbr-ella-shaped valve member having a concaveside facing said seat, said concave side being uniformly curved from its periphery to its center, said member being of pliable material and having a relatively thick center portion tapering toward a thin peripheral portion to provide a relatively rigid interior and a pliable peripheral portion, said peripheral portion when under pressure engaging said convex seating surface with a uniform wiping action,

a valve stem extending from said center portion in a direction away from said valve seat, and a valve guide for said stem.

12. In a chemical pump including a pumping chamber, a reciprocable pumping member, means for reciprocating said pumping member into and out of said pumping chamber, an inlet to said pumping chamber and an outlet from said pumping chamber, self-cleaning check valves in said inlet and said outlet, each of said check valves including an annular' valve seat with an annular convex seating surface, the combination with said seating surface of an improved check valve member of pliable material, said check valve member being of an umbrella-shaped formation with a concave side facing said seat, said concave side being uniformly curved from its periphery to its center, the peripheral portion of said check valve member being thin and exible, and, when under pressure, slidably engageable with said convex seating surface of said valve seat with a uniform wiping action.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 278,068 Wood et al. May 22, 1883 1,447,074 Gorman Feb. 27, 1923 1,982,966 Schweisthal Dec. 4, 1934 2,130,521 Brunner Sept. 20, 1938 2,145,566 Corydon et al. Jan. 31, 1939 2,157,970 Rowlands May 9, 1939 2,185,784 Corydon et al. Jan. 2, 1940 2,260,306 Ferguson Oct. 28, 1941 2,308,974 Harper Jan. 19, 1943 

